Trefoil arch

A trefoil arch, or three-foiled cusped arch (occasionally trilobite arch, no connection to an actual trilobite), is an arch incorporating the shape or outline of a trefoil – three overlapping circles. It has been widely used for its symbolic significance in Christian architecture. Trefoil arches are common in Gothic architecture for portals and decoration. Trefoil or "trilobed" arches are also a characteristic feature of decorated portals in late Fatimid architecture and Mamluk architecture in Egypt, from approximately the 12th to 16th centuries.^{: 191 : 89}

• Trefoil arch in the choir of the parish Church of Saint-Eliphe (13th century), Rampillon, Seine-et-Marne (Ile-de-France)
• Trefoil arches at the Bayeux Cathedral (11th century), Calvados, Normandy, France